Avalanche Forecast
Regions: South Coast.
The seemingly continuous storm cycle continues, with snowfall and strong wind Tuesday night. Wind slabs will form and the snow will continue to load a buried weak layer, where it exists. Sunny skies on Wednesday may rapidly deteriorate the snow on sun-exposed aspects.
Confidence
Moderate - Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.
Weather Forecast
TUESDAY NIGHT: Cloudy with snowfall, accumulation 5 to 15 cm, strong west wind, treeline temperature -3 C, freezing level 1000 m dropping to 600 m.
WEDNESDAY: Mix of sun and cloud, light west wind, treeline temperature -4 C, freezing level 800 m.
THURSDAY: Cloudy with snowfall, accumulation 15 to 30 cm, strong southwest wind, treeline temperature -3 C, freezing level 900 m.
FRIDAY: Mix of sun and cloud with isolated flurries, accumulation 5 cm, light southwest wind, treeline temperature -5 C, freezing level 600 m.
Avalanche Summary
On Tuesday morning, tree bombs, pinwheeling, and small loose dry avalanches were observed. They all occurred naturally and likely failed in the storm snow from Monday night.
Snowpack Summary
The next storm on Tuesday night will drop around 10 cm of snow across the region, followed by some sunny skies. The snow may moisten on sun-exposed slopes but stay dry on shaded slopes. The wind will be strong from the west during the storm, so expect wind slab development in lee terrain features, particularly near ridges.
In some of the region, around 50 to 80 cm of snow overlies a layer of surface hoar on north-facing aspects near and above treeline. The layer has been found to be reactive snowpack tests, such as in this MIN and this MIN. This persistent weak layer warrants investigation and a conservative terrain use strategy. Check out the latest forecaster blog that offers a deeper dive into these conditions.
The remainder of the snowpack is well-settled. The snowpack depth varies from around 250 to 300 cm at the peaks of the North Shore mountains (1400 m), tapering rapidly with elevation.Â
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
Avalanche Problems
Wind Slabs
Wind slab formation will continue Tuesday night, with another storm passing by. Around 5 to 15 cm of snow and strong southwest wind will rapidly form slabs in lee terrain features, particularly near ridges.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Persistent Slabs
A weak layer of feathery surface hoar may be found around 50 to 80 cm deep on northerly aspects around treeline and lower alpine elevations. A persistent slab problem is not typical for the region, and there is high uncertainty with regard to how quickly it will stabilize. Assess the layer in the snowpack prior to entering committing avalanche terrain or adopt a conservative mindset to avoid the problem.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 2.5